1. Field of the Disclosure
The present application relates generally to biological rhythm disorders. More specifically, the present application is directed to a system and method to define drivers of sources associated with biological rhythm disorders, such as heart rhythm disorders.
2. Brief Discussion of Related Art
Heart (cardiac) rhythm disorders are common and represent significant causes of morbidity and death throughout the world. Malfunction of the electrical system in the heart represents a proximate cause of heart rhythm disorders. Heart rhythm disorders exist in many forms, of which the most complex and difficult to treat are atrial fibrillation (AF), ventricular tachycardia (VT) and ventricular fibrillation (VF). Other rhythm disorders are more simple to treat, but may also be clinically significant, including atrial tachycardia (AT), supraventricular tachycardia (SVT), atrial flutter (AFL), supraventricular ectopic complexes/beats (SVE) and premature ventricular complexes/beats (PVC). While under normal conditions the sinus node keeps the heart in sinus rhythm, under certain conditions rapid activation of the normal sinus node can cause inappropriate sinus tachycardia or sinus node reentry, both of which also represent heart rhythm disorders.
Previously, treatment of heart rhythm disorders—particularly complex rhythm disorders of AF, VF and polymorphic VT—has been difficult because the location in the heart that harbors the source of the heart rhythm disorder could not be identified. There have been various theories of how complex rhythm disorders function and clinical applications for treating these complex rhythm disorders. However, none of the applications proved fruitful in the treatment of complex rhythm disorders.
Recently, there has been a breakthrough discovery that for the first time identified sources associated with complex heart rhythm disorders. This technological breakthrough successfully reconstructed cardiac activation information (onset times) in signals obtained from electrodes of catheters introduced into patients' heart to identify rotational activation patterns (rotational sources) or centrifugal patterns (focal sources) that cause a large percentage of the heart rhythm disorders worldwide. Treatment of the heart rhythm disorders can thus be targeted to these rotational or focal sources in the patients' heart to eliminate the heart rhythm disorders. Such treatment can be successfully delivered by ablation, for example.
While a rotational or focal source of a complex heart rhythm disorder can be identified as described above, the inner mechanism of the source—i.e., the core of the rotational source (its likely center of rotation), or origin of a focal source—are not well defined. In some instances, a rotational source may have one or more diffuse sections (activation wave fronts) that generally appear to rotate around a subjective rotation center, but tend to spread out diffusely about a section of the patient's heart. While the diffuse activation wave fronts are associated with the source of the complex rhythm disorder, they may contribute insignificantly to driving the heart rhythm disorder than one or more other activation wave fronts of the rotational source. Similarly, the core of a centrifugally emanating focal source of a complex rhythm disorder has not been well defined.
It has thus far been undefined how to identify the core of a rotational source in contrast to an insignificant ‘passive’ rotation that is not a source of the heart rhythm disorder, or how to identify the origin of a true focal source in contrast to an occasional focal activation that can be secondary to a complex rhythm disorder, rather than its source.
There are no known systems or methods to define the core of a rotational source or the origin of a focal source associated with a heart rhythm disorder.